A fish parasite with a needle-like nose that pierces the intestines of its host has inspired a revolutionary medical invention that could replace surgical staples now used to hold skin grafts in place and close serious wounds.
Researchers at Brigham and Women’s Hospital in Boston, Massachusetts, led by biomedical engineer Jeffrey Karp, say they saw a need for an improved medical adhesive and looked to nature for ideas.
“When we started looking into the parasite literature, we quickly stumbled upon worms and, in particular, this spiny-headed worm that has a needle-like proboscis [nose] that inserts in the intestine of fish ... and only the needles swell, so it kind of mechanically locks into place," said Karp, describing a freshwater-fish parasite called Pomphorhynchus laevis, whose swelling and locking needle-nose design gave his team a model for the new and improved surgical bandage with unique adhesive properties.
Karp's prototype, a microneedle-lined bandage that plumps up when exposed to water, locks painlessly into the patient's subdermal tissue and adheres 3-and-a-half times more strongly than any clinical bandage now in use.
The elongated microneedle tips, made with a rigid plastic core, attach to stiff plastic inner and outer layers of highly absorbent material that is similar to the inside of a disposable diaper. When wet, the needles form a mechanical bond with the tissue.
The microneedle patch is also designed to eliminate two specific problems with surgery involving skin-grafts.
According to Karp, who consulted with Dr. Bo Pomahac, head of face transplant surgery at Brigham and Women’s, when conventional staples hold skin grafts in place, they can produce holes 2-to-3 times larger than the width of the staple itself, allowing for potentially harmful bacterial infections. The grafts, Karp says, are also susceptible to filling with accumulated fluids, which can prevent healing.
“Instead of using staples," Karp said, "we would apply a microneedle patch directly on top of the skin graft that will push down to the underlying tissue and essentially lock that graft in place."
Karp also envisions impregnating microneedle patches with antibiotics and other drugs that would infuse slowly into wounds, helping to keep them clean and quick-healing. Researchers are attempting to develop a microneedle patch that can be used to help seal, and heal, internal organs following surgery.
When it comes to removing the bandage, Karp doesn’t think it would hurt more than pulling out surgical staples, which penetrate skin more deeply than the microneedles on the new bandage patch.
The work by Karp and colleagues was funded in part by the National Institutes of Health. An article describing a new micro-needle surgical bandage is published in Nature Communications